Pumping apparatus



Amig- 394m T. L. SHERMAN PUMPING APPARATUS 3 Sheets-Sheet 1 Filed April 12, 1946 Jaacwfon Aug: 23, W49,

T. L. SHERMAN awmm PUMPING APPARATUS Filed April 12, 1946 3 Sheets-Sheet 2 Aug. 23, W49 T. L. SHERMAN ZAFQLWfi PUMPING APPARATUS Filed April 12, 1946 3 SheetsSheet 5 INVENTOR 85 I 270 ATTORNEYS Patented Aug. 23, 1949 UNITED STATES PATENT OFFICE PUMPING APPARATUS Thomas L. Sherman Springfield, Qhio, assignor to The Steel, Products Engineering (30., Springfield Qhio, a corporation of- Ohio Application April 12, 1946, Serial 1%,. es gsz 1 This invention relates to apparatus tor p .P- o p s ng or bl win as u o l uid fluids, and more particularly to positive displace-- ment apparatus capable of efiective operation at pressures above or belowa-tmospheric; pressure or; pu pin ompr in or low n aseous or liquid fluid and hereinafter referred to as pump ins apparatus. One oi". the principal objects of the invention is to. provide such pumping apparatus which will have. amaximum piston displacement from a Inachine of given diametral dimensions, It is also an object of the invention to provideapparatus of the above type having high o-verallefficiency in operation and which can be economically-and accurately manufactured. 1

An additional object of the invention isto pro, vide such apparatus having positive displacement under all pressure. and speed conditions the out.- put of which is closely proportional to the speed of operation.

' Another object is to provide such pumping ape paratus which will: be compact in shape and of low weight and wherein the use of operated o automatic type valves can be avoided. i

A further object is to provide a simple and effective cooling system for the walls of the cylin- (16 in pumping apparatus of the above type.

A still further object is to provide such appa ratus wherein reciprocating movement is imparted to the pistons through a rotating slant or swash plate without the use of special guides for the bridge members by means of which the pistons are connected together about the peripheryof the swash plate.

A still further object is to provide for simple and effective sealing between the sides of a piston and the adjacent walls of a cylinder such as may be used in apparatus of the above type and which will be effective whether the engaging piston and cylinder surfaces are plane, concave or convex.

Other objects and advantages of the invention will be apparent from the following description, the accompanying drawings and the appended claims.

In the drawings, which illustrate prefer-red embodiments of the invention, and in which like characters of reference designate like parts throughout Fig. 1 is a View in longitudinal section illuss trating amulti-cylindercompressor or blower constructed in. accordance with the present i-nyention;

Fig. 2 is a composite view of; the apparatus shown. i g. the l ft ha f, be ng-11o ertica chine.

16.. claims. (c asm-1st) section on the, 1111524, in .F s.-. i. an the right ha f b i g in levation, oo ing rom e leit inFig.1;f

. a. 3 is. afragm nt ry section roush'tb ro ry valve taken nthel line 33' in Fi Fin 4 is a ragmentary v ew. in section substantia y n he 1ine.4.4 in Fig-1.

- Fig. 5 is a, perspective, View illustrating one of the rotary valve, membe s. mploy d. in h device shown in Figs. 1 to 3;

. F 6 is a fra mentary view partl in elevation and partly broken away and in section illustrating one o th p ston and the packing means th r or utilize n, the appa atus sh wn Figs. 1 to 3.;

g l s nexplode d l vi w n. perspe ti e. of. a c r er f the piston shown. in i 6. mo trating the packing, means utilized therewith;

- Fig. 8 is a detail view in perspective illustrating the pa ts sho n. in- E n as emb posi i n; F s, 91s a v w s m lar to Fi 8 ustrat ns. a modified form of packing means; and F st I0 is a. fra m ntar view. par ly n va: tipn; and, partly in longitudinal section, illustrat, ins a b ow r or ompre so m ng a mod fe cation of the invention. As stated, the present invention is particularly directed to the. provision of positive displacement b mp n pparatus having max m p n isplacement from; apparatus. of given diametral dimensions and} having also: novel structural feas turns, permitting economical and accurate man, puncture, and it. is desired in this connection; to provide a construction equally applicable to apparat lEQ pu pin c mpressin or blowing air or th r e ses:anllieuids:-. '1 accordanne w th the. invention, these o jectives are obtained apparatus wherein the cylintigers are arranged circumferentially about a cena r flow or dischar passage ext ndin substantial-ly the. enti e,- lengt f't e appa a nd whe ein he pist n are re p oca d p r el to this flow passage by: means of a rotating slant or swash plate having its @XiS:.Of rotation substamtiallv oaxial. with th cen ral ass f the a.-

Ihis; basic construction provides for a num r at other tructural featur s. w h n:- tribute to the results achieved by means of the inven io istons a r ad ly ma dou le act n so that they displace substantially twice th volume of the cylinders for each complete cycle of reciprocation and the invention also provides for valve means capable of: directing the entire discharge m all the cyl nder in o the c n l ow p sage us o e wa h plat t m else makes practic l a double end d. pump.-

diametral dimensions utilizing cylinders of circular or other conventional shapes.

The present invention provides positive displacement apparatus which is compact, low in weight and highly efficient. This apparatus has good control characteristics permittingtwo or more to be operated efiectively in parallel. The invention does not require operated ,valves or to the proper degree of accuracy without close tolerances. v

Referring first to the embodiment of the inyention shown in Figs. 1 to 3, and particularly to the structure shown to the left ofthe central plane AA in Fig. 1, cylindrical wall member 25 s and an outer cylindrical wall member 2| are concentrically arranged to form an annular cylinder chamber about a central passage, outer wall member 2| being providedwith cooling fins 22 as shown. This annular cylinder chamber is in turn'separated into a plurality of individual cylinders by wall members 25, which are radially arranged in circumferentially spaced relation between the concentric cylindrical wall members as shown particularly in Fig. 2. As shown, there are nine of these wall members 25, andthey divide the annular cylinder chamber into nine parallel symmetrical cylinders 26 each having in transverse section the general configuration of a sector of a circular annulus. Wall members 25 are shown as held inposition' by engaging in suitable slots in the adjacent surfaces of the cylinder walls 20 and 2!, and each wall member 25 is also provided, as shown, with a plurality of internal passages 21 parallel to the central passage of the apparatus, these passages 21 providing for cooling the walls by passing suitable coolant therethrough as will be described.

The above cylinder construction provides substantial advantages over conventional structures wherein the individual cylinders are circular in transverse section. In the latter type of construction only a limited number of circular cylinders can be provided within given diametral dimensions, and there will inevitably be substantial loss of useful space between and around adjacent cylinders, as can readily be appreciated by visualizing the design produced by' drawin a makes possible the efiective use of this entire cylinder chamber except for the comparatively negligible space occupied by radial walls 25. This economy of manufacture, since the individual parts which form the cylinders are of simple shape and readily manufactured to the proper degree of accuracy.

The outer heads for cylinders '26 are provided by a member 30 secured, as shown, to the outer end of wall member 2| and which includes a closed outer end portion 3| and a circular flange 32 which engages inner wall member 20 adjacent its outer end. Head 30 is provided with openings 33 which serve as intake passages for air from the outer atmosphere, and this air passes to the central passage formed by wall member 26,

whence its further course is controlled by valve means to be described. A plurality of troughlike depressions 34 are provided on the inner side .of head 30, there being one of these depressions 34 for each of cylinders 26 and each bein adapted to register at its radially inner end with one of the corresponding apertures 35 in inner cylinder wall 20, each depression 34 and aperture 35 thus combining to provide a port for communication between the outer end of each cylinder 26 and the central passage of the apparatus, which ports serve alternately for both intake and discharge as will be described. Head 30 is also provided with slots radially arranged and suitably spaced to coincide with radial cylinder walls 25, asshown particularly in Figs. 2 and 4, and radially arranged wall portions 36 enclosing radial passages 31 which provide free communication to or from the ends of passages 21 in these walls 25. A screen 36 is provided for covering intake passages 33 to filter air taken into the apparatus.

The axially inner heads for cylinders 26 are provided by an annular member 40 which is slotted similarly to cylinder head 30 to coincide with the ends of radial wall members 25 and is formed on its surface adjacent cylinders 26 to provide a plurality of trough portions 4| similar to depressions 34 described above each adapted to register with one of the adjacent apertures 42 in inner cylinder wall '20 to provide a port for communication between the central passage and the axially inner end of each cylinder 25. Head member 40 is also formed with boss portions 43 for supporting the piston rods of the apparatus and is provided with a plurality of passages 44 through which coolant may be introduced to the passages 21 within wall members 25, the shape of these passages 44 being clearly shown in Fig. 3. In operation, coolant may be introduced into these radial cylinder walls 25 by positioning the device in an inlet air duct extending between the planes indicated generally at 45 and 46. With this arrangement, air will be directed into passages 44 and thence through passages 21 in each wall member 25 and this air can then exhaust to atmosphere through the outlets 31 at the outer end of the apparatus, as indicated by arrows 41 in Figs. 1, 3 and 4.

mounted, having a circularly convex outer edge, a

circularly concave inner edge, and plane side edges each parallel to its adjacent radial cylinder Wall 25. Since as pointed out, cylinder 26 effectively provide a single annular cylinder chamber of substantially the maximum cross sectional area I v Lfor apparatus of given diameter, the use of the construction has also substantial features of complementarily shaped pistons in these sectorshaped cylinders provides maximum piston displacement for the given diametral dimensions, which as noted is substantially e reaterthan can be obtained from apparatus of the same \diam'etral dimensions using cylinders and pistons of circular or any other shape not termed directly by subdivision oi the annular cylinder space.

Each of pistons 59 is secured, by means such as a. nut and lock washer iii to a piston rod 52 mounted for reciprocating movement in boss '43 of head member 4%, suitable bushings 53 and packings being provided to permit .free reciprocation without leakage from the cylinder: Each piston rod 512 is in turn secured to a ibridgemember 35 3 adapted for embracing contact through slipper bearing elements '55 with a. slant or swash plate 55 mounted for rotation. coaxial ly with the annular cylinder chamber within the central portion of the apparatus and enclosed by annular casing 51. As shown, both piston rod 52 and 'bridge 54 may be made substantially hollow to provide for lightening the total weight of the apparatus, and the resulting open end of the rod adiacent the bridge provides for convenient mounting of the socket mountings for bearing elements '56, as shown in Fig. :1.

As swash plate 55 rotates, it will cause each piston rod 52 and the piston Ell connected-therewith to reciprocate in rotational sequence, and during such rotation slipper bearings 55 will pivot in their sockets to follow the varying presentation of the faces of the swash plate. Furthermore, since these pistons are of sector shape as de scribed and are restrained by their adjacent complementarily formed cylinder walls against rotaition about the axis of rods 52, means such as :a pin 53 :and key 59 may be provided to hold rod *52 and bridge against rotation with respect to the piston, thus making possible the eliminat on of separate guide members for retaining the bridge in the proper alignment for continuous engagement with the rotating swash plate.

The mounting means for swash plate 55 includes cylindrical tube members iii! and tdflwhich are rotatably supported in bearings iii and lfii carried by supporting members 52 and 452 secured to the inner rims of cylinder heads ti! and M9. 'Tube iii? has a flanged inner end which is bolted at 53 to swash plate 55. The similar cylindrical tube member 155 is also bolted at E3 to swash plate 55, and these tube members 6% and 1-60 together extend substantially the entire length of the apparatus and provide a continuous central passage indicated generally t5. Swash plate v55., is connected through radial spokes -51 to an inner hub member '51? which in turn is splincd or otherwise provided with a driving connection to the main drive shaft it. Since spokes it! and hub EB are positioned central passage 66, the spokes are preferably streamlined or made of similarl smooth shape to offer minimum resistance to the passage of air, and a streamlined nose piece H for the inner end of shaft "EB serves simi- 'larly to provide for reducing the resistance of the shaft and hub 63 to the how of air through nassage '56. The stifinessoi spokes til can be selected to offset torsional resonance within the speed range of the engine, and also instead of being formed integrally with the swash plate the spokes may connect with an outer hub which in turn may be sp'lin'ed or otherwise placed in driving connection with the swash plate.

Drive shaft 19 leads to a suitable source of motive power, shown, such as an engine withinithe casing shown fragmentarily at 15. The

enter casing'fragmentariiyshown at I6 is adapted to be fixedly mounted "with respect to the :compressor, :as shown, and forms with casing 155 a passage H continuous with central passage 56., through which .the output of the apparatus is adapted to pass :as will .be explained Casings H5 and iii are shown as secured together through annularly disposed ribs 18 which should be of such design as to avoid offiering undesirable redistance to the flow of air through passage ii.

filo lubricate the swash plate and its asso- Ciiiillbd moving par-ts, head member 40 may be promined at at with an inlet for lubricant, which may be supplied from the main engine pump, this int-ct connecting with an annular conduit 8i from which lubricant may be jetted to he bearing snrltaces of the slant as shown by arrow '85 in 1. ,An oil outlet 82 is provided in casing 53! and may --be attached to a scavenge pump on the main engine.

When the apparatus is operated as described, each piston will make one complete reciprocatory ycle for each 360 of rotation of the swash plate, and during :each half of its cycle it will act to force the air or other workin fluid out through the pent at the cylinder head towards which it is moving and simultaneously to exert suction on the port at the opposite cylinder head. The invention accordingl provides valve means for controlling the passage of fluid through these ports, and the embodiment thereof shown inF-igs. 1 to 3 utilizes rotary valves operating to direct the output of each cylinder through ports into central passage 65 on both strokes of the piston and also to provide for communication from intake openings 33 to the ports whereon the pistons areexertingsuction.

The valve means for control of intake to and discharge from cylinder 26 comprises a pair of generally cylindrical valve members l-Oll and HM mounted on tube member to and provided with a cylindrical spacing piece Hi2. As illustrated, these valve members are identical and member 400 is shownin clearer detail in Fig. 5. The outer end of tube 513 is closed by a disk use bolted to valve member HM, thus closing this end of pas- .sa-ge 55. Valve member M0 is provided with a radially extending projection I65 which is adapted for close engagement with the inner surface of inner cylinder wall 29 and includes a slot I05 adapted to register with port openings 35 in wall 213., and tube is similarly provided with slots 1-01 adapted to register with slot 106. These slots serve to provide .ior discharge into passage from each of cylinders 26 in rotation as the valve rotates, and the circumferential length of slot I66 depends upon the discharge pressure duty of the machine. Valve member IOI is provided with a similar radially extending projection i It having a similar discharge slot H! therein adapted to register with ports 42 in cylinder wall 20 and slots M2 in tube .69. In assembling the pparatus, valve members we and It] will be so positioned that the projections 35 and H0 will lie approximately opposite each other with the slots :106 and 1H approximately at 180 rotation irom each other. This construction leaves a space M5 W-hiohis vannular adjacent spacing piece M2 and partially annular adjacent the projections and H9 and which connects through head member 319 with the intake passages 3.3, thus providing for direct intake to each of cyliniders 2 5 when the ports "35 and 42 are left open by rotation of valve members Hill and m with respect to cylinder wall i211.

With the valve structure as above described and shown, communication is provided between certain of cylinders 26 and the intake passages 33 through space H5 and ports 35 and 42, and between others of cylinders 26 and central passage 66 through slots I05 and ports 35 and through slot I II and ports 42. Accordingly, the valve members I and IN are so designed and constructed and so secured to tube 60 for properly timed rotation with swash plate 55, that there will be open communication between central passage 66 and the end ports of the cylinder 26 towards which the piston 50 therein is moving and open communication between the intake passages and the other end ports, i. e., the ports which the piston is moving away from and thus exerting suction on. Thus in Figs. 1 and 2 it is assumed that shaft 70 is rotating in clockwise direction as viewed in Fig. 3, with the piston 50 in cylinder 26a at the top in these views shown in approximately axially inner dead center position. The remaining pistons will therefore be at various positions between inner and outer dead center, as is indicated in Fig. 2 by showing in elevation the two pistons in cylinders 26?) and 280 adjacent the uppermost piston, since these pistons will be at the right of the section line 2-2 in the position shown in Fig. 1, and the two pistons 26d and 262 in Fig. 2 will be out beyond this section line 22 in Fig. 1 so that only their piston rods 52 show in Fig. 2.

The operation of valve members I30 and IOI in controlling intake and discharge in the operation of the apparatus is shown most clearly in Fig. 3, wherein tube 50 and the valve members carried thereby are assumed to be rotating in clockwise direction. With the parts as shown in Fig. 3, the portion of the projection I05 including the trailing edge of slot I06 is shown as closing the port 42 from the uppermostcylinder 26a, which coincides with the view in Fig. 1 showing the piston 50 in this uppermost cylinder as being at substantially dead center position. At the same time, slot I05 is in register with the ports 42 of cylinders 26b and 260, and it will accordingly be understood that the output from these cylinders passes through slot I05 and slots I01 into the central passage 56. Also, in order to accommodate changes in discharge pressure during operation, the leading edge of slot 806 is formed with a member H5 hinged at Hi to the adjacent por-' tion of projection I05. This construction permits member l I0 to pivot inwardly if the pressure within cylinder 23d becomes too great and so permits the cylinder to begin its discharge to central passage 66 before slot I08 is fully in register with the port 22 of the cylinder. also shown as provided with a suitable counterweight portion H8 and a pin and slot unit H0 serving as a stop to limit its pivotal movement.

In Fig. 3, port @2 of cylinder 26a is shown as closed similarly to cylinder 26a by the leading portion of projection I05. This cylinder 26c will be the next in rotation after cylinder 26d to discharge to central passage 66 as valve member I00 continues to rotate. The ports 22 of cylinders 261, 26g, 26h and 262' are all shown as open to the passage I I5 between the valve structure and cylinder wall 20, so that these ports 42 are serving as intake ports for these cylinders,'with the air entering from intake passages 33 and annular passage 1 95. Fig. 3 also shows in dotted lines the position of slot MI in the projection IIO on valve member IOI and as shown, this slot is in register with the ports 35 of cylinders 261, 26g, and 26h.

Member I Wis Thus these three cylinders will be discharging to central passage 66 through their outer end ports at the same time that cylinders 26b, 26c and 26d discharge through their inner end ports, and as explained, these cylinders 261, 26g and 26h, together with cylinder 261 will at the same time be taking in air through their inner end ports as shown in Fig. 3.

As has already been pointed out, the invention makes practical the use of a double ended structure having a separate set of cylinders at each end of the apparatus with the centrally positioned swash plate operative to reciprocate the pistons of both sets of cylinders. The right hand portion of Fig. 1 illustrates such a construction, and the component parts thereof are to a considerable extent duplicates in structure and function of the corresponding parts already described in connection with the structure shown in the left in Fig. 1. Such parts are accordingly designated in Fig. 1 by reference characters produced by adding to the reference character of the corresponding part at the left hand portion of the structure shown in Fig. 1, and specific description thereof isaccordingly believed to be unnecessary.

Some structural modification of certain of the elements at the right in Fig. 1 is called for to provide for the discharge at this end of the apparatus and for convenient attachment to casing members 15 and 16. As shown, the member I30, which provides the outer heads for cylinders I26, is open at its outer end I3| corresponding to the closed end iii of head member 30, and this open ing is surrounded by an enlarged flange portion I31 to provide for convenient attachment, as by bolting, to casing member I6. Casing I6 is also provided as shown with an outer annular flange I39 adapted for bolting to the outer periphery of head member I30, and suitable apertures I39 are provided in this flange for the discharge of the air or other coolant utilized for cooling radial cylinder walls I25 through passages I21 and I 04 as indicated by arrows I41.

The valve means for cylinders I26 are similar in construction, function and operation to the valve means for cylinders 26 just described. Valve member 200 may be identical in construction with valve members I00 and I 0|, but valve member 20I is somewhat modified in structure to provide for the desired discharge from the outer end of central passage 66. As shown in Fig. 1, valve member 20I includes an annula flange portion 203 which extends through cylinder head I30 and engages the inner rim of outer end I3! of head I30 adjacent casing I6. Spacing piece 202 is substantially the same as the corresponding member I02 at the opposite end of the apparatus, and it and the two valve members 200 and 20| are similarly carried by tube member I60, which includes slots registering with the slots in the projections 205 and M0 on valve members 200 and 20! in the same manner as explained in connection with the other valve members, these slots 2I2 for the outer end ports being shown in Fig. 1. Otherwise the construction at the right hand end of the apparatus as shown in Fig. 1 and its operation are substantially the same as that already described in connection with the opposite end of the apparatus, and no further detailed description is believed necessary.

The above construction provides a variety of advantageous features of the invention in addition to those already pointed out. In operation, for each 360 of rotation of the main shaft and swash plate, each piston will displace approximately twice the volume or its cylinder; and this output will all be deliveredtothe common central passage: 6.6 and thence to: passage ll. The.- totaloutput of the apparatus. will aceordinglybe closelyproportional to; the. speed at which the; shaft and swash. plate are driven. Inthis; connection. should. be noted that this apparatus is readily adaptable connection to sources oi pressure; fluid; other than the outside atmosphere. such connections merely requiring; mechanical modifie cation. of; the intake and discharge passages. For example, the apparatus is highly satisfactory for use in. an airplane, in which the ram. efiect, in flight will serve to, increase the pressure at which. air is suppliedto the intake passages. This same ram effect. will also be useful for directing; air as described into the intakepassages 441 and M4 tor coolant tobe transmitted: to the passages 2:1 andv i211 in radial cylinder wall-w 2 -5 and I25. ltshouldi also be noted that,v the. drections of intake and discharge oi the apparatus can be. readily reversed. simple rotational and functional 31d. justments, of the rotary valve members. The swash. plate construction tor reciprocating. the pistons otters further advantages of overall compactness, light. weight. simplicity of manufacture and effi-ciencyin operation, and in. addition it can readily be made of. sufiicient mass for accurately balancing the reciprocating members.

6 to 8 illustrate. packing means found satisfactory for providing tight sealing between the sides. oi. each of the pistons shown in Figs. 1 to. 3 and the inner walls. of the cylinder wherein. each oi said. pistons reciprocates. In Figs. 6 to 8,. piston 2w has each of its sides grooved to receive packing. material, there being two; such grooves Mt inthe. outer and piston sides spaced axially with respect to.- each other anda single groove 142 in the plane piston sides, this groove. 243 being; spaced axially substantially intermediate. grooves. 24%.. Packing members. 243:, 244 and 24.5, of suitable material are adapted to engage in these grooves and are formed, as shown portion-- larly in Figs. "1. and. 8., so thatthe: portions thereof. adaptedlior engagement in each individual groove in the piston overlap at their ends to provide in.- creased packing. material at each corner where leakage would be most likely to occur. Each groove 24!. and 242. also has mounted therein a sinuous metal. spring 2.46 between the inner wall of the. groove and the packing material, these springs, being operative to urge the packing material. outwardly from the. slot into, yielding en.- a ement, with the. adjacent cylinder wall to increase. the tightness, of packing.

9, shows. a modified form of the. packing means shown in 6 to 8. In Fig.v 9;. piston 241' has. only a single groove in each. side thereof, but these grooves. are axially spaced with respect to each other and. packing members andv zee which. overlap, at. the corners: in the, same mannor as in the construction shown in Figs. 6, to- 8 It will be, seen that this arrangement. also. provides for increased thickness. of packing, material. at each corner of the piston as. opposed to, the amount of packing material along the sides. sinuous springs such as, those shown at 245 in Fig. 6 may also be used with the construction shown in Fig. 9. to urge the. packing material into the desired. yielding engagement with the. adjacent cylinder wallsi Fig. 10 illustrates a blower or compressor having stru tural and operational features. ad vantages. similar to those just. described in corn motion. with Figs. 1 to 3 but embodying a modified liQ 10 structure including a. plurality of. automatic op pet or plate type valves. instead of rotary valves such as: are: shown in Figs 1 to. 3.. In Fig. 1.0,; inner and outer circular walls 250 and. 25.! form an annular. cylinder chamber which may be scnarated by radial walls as: described in con-' nection with. 1- to 3 into a. plurality of parallel cylinders 215.2. arranged about. a. hollow Cell trail passage 253. equivalent to passage 66 in Fig. 1.. Piston 25/1 corresponds to pistons 50 and is simil-arly mounted on piston rod 255- for. reciprocating: movement parallel to the. axis; of passage; 253c Piston. rod 255, mounted by means of bushing; 25a for sliding movement. in an annular member 2-5-1 and. is actuated through bridge 2.58, slipper bearingsZES: and swash late. 268, the. latter being shown as mounted tor rotation with hollow shaft. 26.! supported. in bearings. 262 carried by a. suitable seat 2.63 provided by an inner portion oii member 251;. The clearance between the slant shait and member 25.! is. exaggerated in Fig. l for clarity,. but, in practice it may be only or the; order. of a few thousaniths of. an inch If necessary more; elaborate labyrinthine; packings may be. employed.

Member 25% is shown. as having in cross-section the general. configuration of a pair of annular. concentric channel: members and provides an annular chamber 26!! opening inwardly into central passage253= and a second. annular chamber 265 open to, the. outside atmosphere. Member 2.5!- also provides; the axiallyinncr end wall. for each ylinder 252, wall being. provided with intake and dischar e passages. 2.6.6 and. 26.1, respective. which. are in turn controlled by suitable pen pet valves. 26.8 and 2919i Intake. passages- 26 6, communicate with chamber 255 and thence. with the outer atmosphere. and this. chamber is also shown as provided with a. screen are for present. mgr dint particles and the like from being drawn into the apparatus. Intake valve 26.8w is mounted on valve stem 21!. tor sliding movement.- with respectto intake. passages 2:6 8v and. is controlled by a suitablecoit spring, 21.2. normally urging it to closed position Discharge valve 26.9 is mounted tor sliding movement on valve stem 213 carried by member 25,! and is. similarly nor.- mally urged to closed. position by coil spring. 2.111.

The. axially outer end wall for each cylinder 2.52is' formed. by a. member. 21.5. which includes a. central chamber 216 connecting directly with central passage 253. and. an annular outer chamber Zl'l open to. the. atmosphere. and shown as provided with a. cover screen 218. similar to screen 21d. Member 215 is provided with intake. and discharge passages are and 28.0 for each. cylinder 252. controlled by poppet valves 28! and 28.2 reactively. Intake. passages. 215 open. into annular'chamber 211;, and. valve. Zill. is. mounted on. valve stem 283 for. sliding movement inwardly against spring. 281 Discharge passages, 28!! open into central chamber 2.16 of. member 2.15. and thence into central passage 2531 and valve 2.82 is. accordingly mounted for sliding. movement on stem 285; against spring, 286..

With the construction as. described and shown in Fig.- 10', as each. piston 254 reciprocates in. its cylinder 252,. acycle. oi intake and discharge similar to that described. in connection with. Figs; 1 to 3. will take. place. Thus with piston. 254 in thenosition shown in Fig. 101,. discharge valve 282 at. the outer end of. cylinder Z52 be openas under pressure tram the piston to permit passage or flu-id from within. the. cylinder into chamber 216 and thence to central passage 253.,

and intake valve 281 will be forced shut under the pressure from the piston. At the same time, the suction behind the piston will have resulted in drawing intake valve 268 open against its spring as shown to draw in air through channel 265, while the discharge valve 269 at the inner end of the cylinder has been held shut by this same suction effect from'the piston. As swash plate 260 rotates from the position shown in Fig. 10, piston 254 will reverse its stroke and the reverse operation of valves will take place, with valves 269 and 28l opening and valves 268 and 282 being held closed until the piston reaches the end of its inward stroke and again begins it outward stroke. It will be understood that the structure shown in Fig. may have a plurality of cylinders and pistons as described in connection with Figs; 1 to 3, including a second plurality of cylinders on the opposite side axially of swash plate 260, so that the net effect will be closely comparable to that in connection with that shown in Figs. 1 to 3. With this construction, the discharge from the cylinders passes through the center of the machine and through the central boss of the slant member towards the end at which discharge is desired as with the apparatus shown in Fig. 1. The packing means shown in Figs. 6 to 9 are also applicable to pistons 254 in the structure shownin Fig. 10.

While the forms of apparatus herein described constitute preferred embodiments of the invention, it is to be understood that the invention is not limited to these precise forms of apparatus, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims.

What is claimed is: V

1. In a positive displacement pumping apparatus of the character described, the combination of inner and outer circular wall members of different diameters concentrically arranged and forming an annular cylinder chamber about a central passage, wall members radially arranged in said annular chamber and separating said chamber into a plurality of parallel cylinders circumferentially arranged about said central passage, each of said cylinders having in transverse section the general configuration of a sector of a circular annulus, a piston mounted in each of said cylinders for reciprocating movement parallel to said central passage, each said piston being substantially complementary in shape to the cylinder wherein it is mounted, and means for imparting reciprocating movement to said pistons.

2. In a positive displacement pumping apparatus of the character described, the combination of inner and outer circular wall members of different diameters concentrically arranged V and forming an annular cylinder chamber about a central passage, wall members radially arranged in said annular chamber and separating said chamber into a plurality of parallel cylinders circumferentially arranged about said central passage, each of said cylinders having in transverse section the general configuration of a sector of a circular annulus, a piston mounted in each of said cylinders for reciprocating movement parallel to said central passage, each said piston being substantially complementary in shape to the cylinder wherein it is mounted, port means providing communication between each of said cylinders and said central passage, and between each of said cylinders and the exterior of said apparatus, means for imparting reciprocating 12 movement to said pistons, and valve means for controlling said port means to establish proper pumping relation in accordance with the direction of motion of said pistons.

3. In a positive displacement pumping apparatus of the character described, the combination of inner and outer circular wall members of 'different diameters concentrically arranged and forming an annular cylinder chamber about a central passage, wall members radially arranged in said annular chamber and separating said chamber into a plurality of parallel cylinders circumferentially arranged about said central passage, each of said cylinders having in transverse section the general configuration of a sector of a circular annulus, a piston mounted in each of said cylinders for reciprocating movement parallel to said central passage, each said piston being substantially complementary in shape to the cylinder wherein it is mounted, port means adjacent each end of each of said cylinders, means providing communication between said port means and said central passage, means providing communication between said port means and the exterior of said apparatus, means for imparting reciprocating movement to said pistons, and means including valve means for controlling communication to and from said port means to establish proper pumping relation in accordance with the direction of motion of said piston.

4. In a positive displacement pumping apparatus of the character described, the combination of inner and outer circular wall members of different diameters concentrically arranged and forming an annular cylinder chamber about a central passage, wall members radially arranged in said annular chamber and separating said chamber into a plurality of parallel cylinders circumferentially arranged about said central passage, each of said cylinders having in transverse section the general configuration of a sector of a circular annulus, a piston mounted in each of said cylinders for reciprocating movement parallel to said central passage, each said piston being substantially complementary in shape to the cylinder wherein it is mounted, port means adjacent each end of each of said cylinders, means providing communication between said port means and said central passage, means providing comunication between said port means and the exterior of said apparatus, means for imparting reciprocating movement to said pistons, and means including valve means for controlling said port means to open communication between said central passage and the end port of each cylinder toward which the piston therein is moving and substantially simultaneously to close communication between said central passage and the other end port of each said cylinder.

5. In a positive displacement pumping apparatus of the character described, the combination of inner and outer circular wall members of dif-v ferent diameters concentrically arranged and forming an annular cylinder chamber about a central passage, wall members radially arranged in said annular chamber and separating said chamber into a plurality of parallel cylinders circumferentially arranged about said central passage, each of said cylinders having in transverse section the general configuration of a sector of a circular annulus, a piston mounted in each of said cylinders for reciprocating movement parallel to said central passage, each said piston being substantially complementary in shape to the cylgamers index" wherein it; ismmm-ted port means adjacent each end of each of said cylinders; means providing communication between said port means and said central passage, means including a rotary member for imparting reciprocating movement to said pistons. inv rotational sequence, and means actuated by said rotary member and including valve means for controlling said port means operative to open communication between said central passage and the end port of each cylinder toward which the piston therein is moving, substantially simultaneously to close communication between said central passage and the other end port in each said cylinder and open communication between said other: end port and an intake passage, and to reversev said operations. when the direction of piston motion reversed;

6. In a positive displacement pumping apparatus of the character described, the combination of inner and outer circular wall members of different diameters concentrically arranged and forming an annular cylinder chamber about a central passage, wallmembers radially" arranged in said annular chamber and separating said into a plurality of parallel cylinders circurnferentially arranged about. said central passage, each of said cylinders having in transverse section the general configuration of a sector of a'circular annulus, means providing in eachof said radial walls a plurality of passages for coolant substantially parallel to.- said central: passage, means providin ports for intake and discharge of coolant at opposite ends of'said passages, a piston mounted in each of said cylinders for reciprocating movement parallel to said central passage, each said piston being substantially complementary in shape to the cylinder wherein it is mounted, and means. for imparting reciprocating movement to said pistons.

7. In a positive displacement pumping apparatus of the character described, the combination o-l" inner and outer circular wall members of differcnt diameters: concentrically arranged and forming an annular cylinder chamber about a central passage, wall-members radially arranged in annular chamber and separating said chamber into a plurality of parallel cylinders circumferentiallv arranged about said central paseach said cylinder having in transverse section the general? configuration of a sector of a circu ar annulus, means providing in each of said radial walls a plurality of passages for coolant substantially parallel to said central passage, means providing ports tor intake and discharge of coolant at opposite ends of said passages, a

piston mounted in each said cylinder for reciprocatin movement parallel tosaid central passage, each said piston being substantially complementary in shape to the cylinder wherein it is mounted, a swash plate mounted for rotation with a shaft substantially coaxial with said central passage, a piston rod fixedly connected with each of said pistons, a bridge member fixedly connected with each said piston rod and including portions adapted to embrace said swash plate, means for rotating said swash plate to impart reciprocating motion to said pistons, each said piston coacting with its adjacent cylinder walls to prevent rotation of bridge means, port means providing communication between each of said cylinders andv said central passage and between each of said cylinders the outside atmosphere, and means for controllin said port means to establish proper pum ing relation in accordance withv the dire lien or motion 0t said. pistons,

8*. In a positive displacement pumping appara tors of the character described, the combination of inner and outer circular Wall members of different diameters concentrically arranged and forming an annular cylinder chamber about a central passage, wall members radially arranged in said annular chamber and separating said chamber into a plurality of parallel cylinders circumferentially arranged about said central passage, each of said cylinders having in transverse section the general configuration of a sector of a circular annulus, a piston mounted in each of said cylinders for reciprocating movement parallel to said central passage, each said piston being substantially complementary in shape to the cylinder wherein it is mounted, means providing substantially air-tight engagement between the periphery of each said piston and the inner walls of the cylinder wherein it is mounted and including packing means positioned in a groove in each side of each said piston and yieldable means urging said packing means into contact with the adjacent cylinder wall, and means for imparting reciprocating movement to said pistons.

9'. In a positive displacement pumping apparatus of the character described, the combination of inner and outer circular wall members of different diameters concentrically arranged and forming an annular cylinder chamber about a central passage, wall members radially arranged in said annular chamber and separating said chamber into a plurality of parallel cylinders circumferentially arranged about said central passage, each of said cylinders having in transverse section the general configuration of a sector of a circular annulus, a piston mounted in each of said cylinders for reciprocating movement parallel to said central passage, each said piston being substantially complementary in shape to the cylinder wherein it is mounted, means providing a groove in each side of each said piston, a packing member mounted in each said groove, sinuous spring means positioned in each said groove between the inner wall thereof and the packing member therein and operative to urge, said packing member into yielding engagement with the adjacent wall of said cylinder, and means for imparting reciprocating movement to said pistons.

10. In a positive displacement pumping apparatus of the character described, the combination of inner and outer circular wall members of different diameters concentrically arranged and forming an annular cylinder chamber about a central passage, wall members radially arranged in said annular chamber and separating said chamber into a plurality of parallel cylinders circumferentially arranged about said central passage, each of said cylinders having in transverse section the general configuration of a sector of a circular annulus, a piston mounted in each of said cylinders for reciprocating movement parallel to said central passage, each said piston being substantially complementary in shape to the cylinder wherein it is mounted, means providing a groove in each side of each said piston, the grooves in adjacent piston sides being spaced axially with respect to each other and overlapping at their adjacent ends, a packing member mounted in each said groove with the ends thereof overlapping the adjacent ends of the: packing members in adjacent grooves and providing increased packing material atv each corner of said piston, yieldable means positioned in each said groove between the. inner wall 15 thereof and the packing member therein and perative to urge said packing member into yielding engagement with the adjacent wall of said cylinder and means for imparting reciprocating movement to said pistons.

11. In a positive displacement pumping apparatus of the character described, the combination of inner and outer circular wall members of different diameters concentrically arranged and forming an annular cylinder chamber about a central passage, wall members radially arranged in said annular chamber and separating said chamber into a plurality of parallel cylinders circumferentially arranged about said central passage, each of said cylinders having in transverse section the general configuration of a sector of a circular annulus, a piston mounted in each of said cylinders for reciprocating movement parallel to said central passage, each said piston being substantially complementary in shape to the cylinder wherein it is mounted, a swash plate mounted for rotation about an axis substantially colinear with the axis of said central passage, bridge means providing a reciprocable connection between each of said pistons and said swash plate, said bridge means being fixedly connected to each said piston, and means for rotating said swash plate to impart reciprocating motion to said pistons, each said piston coacting with its adjacent cylinder walls to prevent rotation of said bridge means.

12. In a positive displacement pumping apparatus of the character described, the combination of inner and outer circular wall members of different diameters concentrically arranged and forming an annular cylinder chamber about a central, passage, wall members radially arranged in said annular chamber and separating said chamber into a plurality of parallel cylinders circumferentiall arranged about said central passage, each said cylinder having in transverse section the general configuration of a sector of a circular annulus, a piston mounted in each said cylinder for reciprocating movement parallel to said central pas-sage, each said piston being substantially complementary in shape to the cylinder wherein it is mounted, a swash plate mounted for rotation with a shaft substantially coaxial with said central passage, a piston rod fixedly connected with each of said pistons, a bridge member fixedly connected with each said piston rod and including portions adapted to embrace said swash plate, means for rotating said swash plate to impart reciprocating motion to said pistons, each said piston coacting with its adjacent cylinder walls to prevent rotation of said bridge means, port means providing communication between each of said cylinders and said central passage and between each of said cylinders and the outside atmosphere, and means for controlling said port means to establish proper pumping relation in accordance with the direction of motion of said pistons.

13. In a positive displacement pumping apparatus of the character described, the combination of inner and outer circular wall members of different diameters concentrically arranged and forming two parallel annular cylinder chambers about a central passage and spaced axially from each other, wall members radially arranged in each said annular chamber and separating said chambers into two groups of parallel cylinders circumferentially arranged about said central passage, each said cylinder having in transverse section the general configuration of a sector of a 16 circular annulus, a piston mounted in each said cylinder for reciprocating movement parallel to said central passage, each said piston being substantially complementary in shape to the cylinder wherein it is mounted, a swash plate mounted for rotation with a shaft substantially coaxial with said central passage and extending outwardly into said space between said cylinder chambers, means including a piston rod and a bridge providing a connection between each piston in one said group of cylinders and a piston in the other said group of cylinders, each bridge including portions constructed for embracing contact with said swash plate, means for rotating said swash plate to impart reciprocating movement to said pistons, port means providing communication between each said cylinder and said central passage and between each said cylinder and the outside atmosphere, and valve means for controlling said port means to establish proper pumping relation in accordance with the direction of motion of said pistons.

14. In a positive displacement pumping apparatus of the character described, the combination of inner and outer circular wall members of different diameters concentrically arranged and forming two parallel annular cylinder chambers about a central passage and spaced axially from each other, wall members radially arranged in each said annular chamber and separating said chambers into two groups of parallel cylinders circumferentially arranged about said central passage, each said cylinder having in transverse section the general configuration of a sector of a circular annulus, a piston mounted in each said cylinder for reciprocating movement parallel to said central passage, each said piston being substantially complementary in shape to the cylinder wherein it is mounted, a swash plate mounted for rotation with a shaft substantially coaxial with said central passage and extending outwardly into said space between said cylinder chambers, said swash plate being provided with a passage therethrough adjacent its center and coinciding with said central passage, means including a piston rod and a bridge providing a connection between each piston in one said group of cylinders and a piston in the other said group of cylinders, each bridge including portions constructed for embracing contact with said swash plate, means for rotating said swash plate to impart reciprocating movement to said pistons, port means providing communication between each said cylinder and said central passage and between each said cylinder and the outside atmosphere, and valve means controlling said port means and operative in accordance with the direction of motion of said pistons to direct substantially the entire output of said cylinders into said central passage and to one end of said passage and apparatus.

15. In a positive displacement pumping apparatus of the character described, the combination of inner and outer circular wall members of different diameters concentrically arranged and forming two parallel annular cylinder chambers about a central passage and spaced axially from each other, circumferentially spaced wall members radially arranged in each said annular chamber and separating said chamber into two groups of parallel cylinders circumferentially arranged about said central passage, each said cylinder having in transverse section the general configuration of a sector of a circular annulus, a piston mounted in eachsaid cylinder for reciprocating movement parallel to said central passage, each said piston being substantially complementary in shape to the cylinder wherein it is mounted, a swash plate mounted for rotation with a shaft substantially coaxial with said central passage and extending outwardly into said space between said cylinder chambers, means including a piston rod and a bridge providing a connection between each piston in one said group of cylinders and a piston in the other said group of cylinders, each bridge including portions constructed for embracing contact with said swash plate, means for rotating said swash plate to impart reciprocating movement to said pistons, port means adg'acent each end of each said cylinder, means providing communication between said port means and said central passage and between said port means and the outside atmosphere, and rotary valve means mounted for rotation with said swash plate for controlling said port means and operative to open communication between said central passage and the end port of each cylinder toward which the piston therein is moving, substantially simultaneously to close communication between said central passage and the other end port in each said cylinder and open communication between said other end port and an intake passage, and to reverse said operations when the direction of piston motion is reversed.

16. In a positive displacement pumping apparatus of the character described, the combination of inner and outer circular wall members of different diameters concentrically arranged and forming two parallel annular cylinder chambers about a central passage and spaced axially from each other, wall members radially arranged in each said annular chamber and separating said chambers into two groups of parallel cylinders circumferentially arranged about said central passage, each said cylinder having in transverse section the general configuration of a sector of a circular annulus, a piston mounted in each said cylinder for reciprocating movement 18 parallel to said central passage, each said piston being substantially complementary in shape to the cylinder wherein it is mounted, means providing a groove in each side of each said piston, a packing member mounted in each said groove, sinuous spring means positioned in each said groove between the inner wall thereof and the packing member therein and operative to urge said packing member into yielding engagement with the adjacent cylinder Wall, a swash plate mounted for rotation with a shaft substantially coaxial with said central passage and extending outwardly into said space between said cylinder chambers, means including a piston rod and a bridge providing a connection between each piston in one said group of cylinders and a piston in the other said group of cylinders, each bridge including portions constructed for embracing contact with said swash plate, means for rotating said swash plate to impart reciprocating movement to said pistons, each piston coacting with said packing means and the adjacent cylinder walls to prevent rotation of the bridge connected therewith, port means providing communication between each said cylinder and said central passage and between each said cylinder and the outside atmosphere, and valve means for controlling said port means to establish proper pumping relation in accordance with the direction of motion of said pistons.

THOMAS L. SHERMAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 588,735 Schuster Aug. 24, 1897 2,070,880 Blum Feb. 16, 1937 FOREIGN PATENTS Number Country Date 163,857 Great Britain June 2, 1921 

